Generally, a flow meter is a device used to measure the flow rate or quantity of a gas or liquid moving through a pipe. Flow measurement applications are very diverse and each situation has its own constraints and engineering requirements. Flow meters are referred to by many names, such as flow gauge, flow indicator, liquid meter, etc. depending on the particular industry. However the function of the flow meter, to measure flow, remains the same.
Precision flow meters are used to provide accurate monitoring and/or flow control. Some industrial applications require precise calculation of quantity, such as precision servo-valve development for the aerospace industry. On the other hand, an application to measure water flow to a vineyard may only require a measurement accuracy of 5% to 10%.
There exists various types of flow meters based on different parameters, such as positive displacement, mass, and velocity. Positive displacement (PD) flow meters are unique as they are the only meter to directly measure the actual volume. All other types infer the flow rate by making some other type of measurement and equating it to the flow rate. With PD meters, the output signal is directly related to the volume passing through the meter. Includes bi-rotor types such as gear, oval gear, helical gear, disc, reciprocating piston, and oscillating or rotary piston.
In mass based flow meter, the output signal is directly related to the mass passing through the meter. Thermal and Coriolis flow meters fall into this category. In velocity based flow meter, the output signal is directly related to the velocity passing through the meter.
A common flow meter like a differential pressure and positive displacement flow meters is the magnetic flow meter, also technically an electromagnetic flow meter or more commonly called as mag meter. A magnetic field is applied to the metering tube, which results in a potential difference proportional to the flow velocity perpendicular to the flux lines. The physical principle at work is based on electromagnetic induction. The magnetic flow meter requires a conducting fluid, for example, water that contains ions, and an electrical insulating pipe surface. The magnetic flow meters is performed based on induction of conductive fluids resulting from passage through a coil. The induced electrical current in the coil is a measure of flow rate. So, these types of flow meter works only on conductive fluids.
Currently, a novel method for flow rate measurement are based on actuation of sensitive components that are directly in contact with the fluid. Physical or chemical characteristics of these component alter via the fluid parameters such as velocity, temperature, etc. currently some kind of hierarchical structures obtained from lithography and replica molding methods are being used as sensitive components of measurement devices. The methods such as lithography, are usually time consuming and costly.
Thus, there exists a need for a simple and ergonomic flow meter that solves the problem of accounting low electrical conductivity of some fluids in flow rate measurement, as seen a limitation in the existing magnetic flow meters. Further, there is a need for a sensitive component fabricated by a field directed assembly of magnetic materials that could be used in the flow rate measurement. Application of such fabrication method of the sensitive component not only results in reduction of production costs, but also resolves some complex issues such as, template preparation in existing lithography and replica molding methods.